1. Field of the Invention
The present invention generally relates to an illuminating device, and more particularly, it relates to an illuminating device capable of waterproof function and heat-dissipating function.
2. Description of Related Art
The light-emitting diode (LED) is a semiconductor device, mainly made of compound semiconductor materials of chemical elements of groups III-V, for example, gallium phosphide (GaP), gallium arsenide (GaAs). The compound semiconductor materials are characteristic of converting electric energy into light. In more details, when applying a current on the compound semiconductor material, the electrons and the holes in the material would be recombined and the excessive energy after the recombining would be released in light form so as to result in light-emitting effect.
In general speaking, the light-emitting phenomena of LEDs are counted as cold light emission instead of light emission resulting from heat or discharge light emission. Thereby, the lifetime of an LED can be over a hundred of thousand hours and the LED can work immediately without idling time. In addition, LEDs have many advantages, such as fast response speed (about 10−9 sec), small size, power-saving, low pollution (no mercury) and suitability for mass production. In this regard, the LEDs are applicable to various and wide fields, for example, light sources in mega-size display board, traffic light, handset, scanner or fax machine.
Since the light-emitting luminance and the light-emitting efficiency of LEDs are gaining steady advances recently and the white LEDs with high luminance have been in mass production, so that the white LEDs are gradually used in illuminating devices, for example, indoor lighting, outdoor street lamps and illumination lamps in refrigerator or in water. The LEDs with high power generally encounter a heat-dissipating problem. That is if an LED is operated in an excessive high temperature, it likely occurs that the light luminance provided by the LED gets decayed and the lifetime thereof is shortened.
Besides, when LEDs serve as illumination lamps in refrigerator or in water, except for heat-dissipating consideration, it is also considered to have waterproof effect so as to avoid moisture from electrically damaging the structure inside a lamp, in particular the problem occurring at the joint with gap between the lens and the heat sink block thereof. As the waterproof handling scheme involved in the illumination lamps in refrigerator or water currently, it is mostly adopted a processing in filling adhesive on the joint with gap between the lens and the heat sink block thereof so as to conduct a gap filling processing. However, such a processing in filling adhesive is unlikely controlled and results in a poor effect. Another adopted scheme is to make the heat sink block directly enclosed in the lens where the waterproof design is only against the side edges of the lens, wherein, however, the heat sink block directly enclosed by the lens is not easily to be heat-dissipated so that the LEDs would be operated in an excessive temperature to reduce the reliability of the LEDs. In this regard, to make a lamp adopting LEDs and having good design of heat-dissipating function and waterproof function has become one of projects attended by many developers.